Identification of silverleaf nightshade using microsatellite markers and microstructure

Silverleaf nightshade (Solanum elaeagnifolium Cav.) originated in America and is a serious summer-growing perennial weed in Australia. It is often confused with the native Solanaceae species quena (S. esuriale Lindl.). Both belong to the -Leptostemonum' subclass in the Solanaceae and are remarkably similar in their morphological traits. Correct identification is critical for the successful management of S. elaeagnifolium, as different biotypes could vary significantly in their response to control measures, such as herbicides and biocontrol agents. In order to improve the identification of S. elaeagnifolium, DNA polymorphism and microstructure of S. elaeagnifolium and S. esuriale were compared. Thirteen cross-species simple sequence repeat (SSR) primer pairs were utilized to investigate the polymorphism between S. elaeagnifolium and S. esuriale. SSR markers clearly separated the two species. Three unique SSR alleles were present in S. esuriale but not in S. elaeagnifolium, which could be used to distinguish the two species. Scanning electron microscope (SEM) examination of the microstructure of the leaf surface of these two species showed that the complex stellate trichomes on the upper leaf surface of S. elaeagnifolium had a deep -root' structure penetrating into the palisade mesophyll, while this structure was not found in S. esuriale. Combination of molecular phylogeny and SEM will considerably assist in the correct identification of S. elaeagnifolium.